The use of light emitting diodes (LEDs) in electronic products is ever-increasing and in some cases are replacing traditional light sources, such as light bulbs, in existing applications. For example, LEDs can now be found in flashlights, automotive headlights and backlight units for LCD screens.
Ceramics such as alumina oxide (Al2O3) or aluminum nitride (AlN) are used in the packaging of high brightness LEDs. In addition to ceramics, plastic leadless chip carriers (“PLCC”) and other leadframe configurations are also used. These types of packages often have large footprints, poor thermal conductivity and large mechanical tolerances and are not flexible to design changes, thus making application-specific designs difficult.
As features and capabilities of consumer electronic products grow, there is an increasing need to fit more circuit elements (e.g., electrical circuit components, integrated circuit dies, LEDs, thermistors, diodes, rectifiers, temperature sensors, and LED drivers) in a smaller space. Typically, the dimensions of a printed circuit board (PCB) are dictated by the size of the consumer electronic product and the available space within the product. For example, in some consumer electronics such as mobile phones or other handheld products, the height of an assembled PCB (e.g., the circuit elements mounted on both sides of the PCB) is limited to be about one millimeter (mm), whereas the typical height of the assembled PCB is 1.5 mm (a typical height of a PCB is 500 microns (μm) and a typical height of circuit elements is 500 μm). Therefore, either the size of the assembled PCB must be reduced or features and capabilities must be reduced to fit the assembled PCB into the limited available space. In addition, thermal performance of the circuit elements is also a consideration.